v3.0.4

Changed:

• METS Server: downgrade log messages (INFO→DEBUG), #1305

Fixed:

• METS Server: make add_file (POST /file) work with pageId=None, #1305
• PAGE API: serialization of OrderedGroup/* namespace prefixes, #1305
• run_processor: handle frozendict and empty parameter when logging, #1305

Added:

• tests for processors with add_file(... page_id=None ...), #1305
• tests for ocrd_page roundtrip, #1305
• tests for processor logging, #1305